The United States Environmental Protection Agency ("EPA") recently finalized the first of several pending guidance documents and regulations governing the evaluation and mitigation of vapor intrusion at contaminated sites, a growing area of focus that has thus far been regulated primarily on the state level. EPA’s new guidance requires regional EPA offices to address vapor intrusion risks during the five-year reviews for most completed Superfund cleanups.

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Vapor intrusion, the migration of hazardous vapor from contaminated soil or groundwater into overlying buildings, is of greatest concern at sites contaminated by volatile organic compounds ("VOCs"), such as chlorinated solvents perchloroethylene ("PCE" or "Perc") and trichloroethylene ("TCE"), as well as several non-chlorinated gasoline components. In 2002, EPA issued draft guidance governing the investigation of vapor intrusion at Resource Recovery and Conservation Act ("RCRA") corrective action, Superfund, and Brownfield sites, but it has yet to finalize that document. The 2002 Draft Guidance did not cover vapor intrusion from petroleum releases at underground storage tank ("UST") sites, and a recent scientific analysis for EPA concluded that “screening for [petroleum vapor intrusion, or "PVI"] using the same methodology for chlorinated hydrocarbons is overly conservative; a different approach is needed for PVI."

EPA's latest guidance covers only Superfund sites where the selected remedy leaves residual amounts of hazardous substances at concentrations that do not allow for unlimited use and unrestricted exposure, thus requiring five-year reviews of remedial protectiveness. As part of that five-year review process under the federal Superfund law, EPA plans to gather data on existing and potential vapor intrusion pathways, assess the protectiveness of the selected remedy in light of any such pathways, and "if issues are identified that may prevent the response action from being protective, now or in the future... [to document] these issues and the follow-up recommendations and actions... in the five-year review report." This analysis could result in the "re-opening" of longstanding Superfund remedies to address vapor intrusion, similar to a re-evaluation process that New York State initiated in 2006 at chlorinated VOC contaminated sites overseen by the state Department of Environmental Conservation ("DEC").

While EPA's recent guidance provides a series of questions for use in evaluating potential vapor intrusion risks, it does not detail screening and testing procedures for sites where vapor intrusion is suspected. Those topics were addressed in EPA's 2002 Draft Guidance, which remains under review and is anticipated to be finalized in 2013.